What was the largest volcanic eruption in the 20th century?

The largest eruption in the world in the 20th century occurred in 1912 at Novarupta on the Alaska Peninsula. An estimated 15 cubic kilometers of magma was explosively erupted during 60 hours beginning on June 6th. This volume is equivalent to 230 years of eruption at Kilauea (Hawaii) or about 30 times the volume erupted by Mount St. Helens (Washington) in 1980!

Due to the remote location of the eruption, scientists did not visit the site until 1918, when they found the Ukak River valley filled with volcanic deposits and steaming fumaroles. They called it the "Valley of Ten Thousand Smokes".

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-- a Centennial perspective of the Novarupta-Katmai eruption, the largest of the 20th century

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Bill Burton discusses the June 6-8, 1912 eruption of Mount Katmai in Alaska which was 30 times larger than the eruption of Mt. St. Helens in 1980. This eruption caused widespread devastation, and inspired heroic efforts at survival by the local people. Burton returns to this topic a century later and explains what lessons the Mount Katmai eruption provides for modern-day monitoring of volcano hazards.

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View southeast from Overlook Cabin looking over the Valley of Ten Thousand Smokes. The pyroclastic and ash deposits that fill the valley remain nearly vegetation-free more than 100 years after the 1912 Novarupta-Katmai eruption.